Who in the world is free from sin as even a born again believer stumbles at times. God accepts us as who we are and if our hearts are willing will provide for the necessary refinements. This advice you have provided is naïve and if followed will result in a lifetime of waiting for Mr. Perfect or Miss Right. If you wait for all of the lights to turn to green and for all of the 'T's' and 'I's" to be crossed before proceeding forward in a relationship you are going to be waiting for a very long time.
Yes. And isn't there scripture about the partners santifying each other. Marriage is what helps in the sanctification process. But, I have to admit I have been sent some devils and counterfeits, and they were the answers to some parts of my prayer, but I do not believe that was God. Who knows....lol